Draft apparatus.



J. K. & A. 0. MILLER.

DRAFT APPARATUS.

APPLICATION FILED JAN. 19. 1911.

Patented Aug. 20, 1912.

WITNESSES:

UNITED STATES PATENT OFFICE.

30m; x. MILLER sup ALLEN o. MILLER, or SEATTLE, wasnm'e'ron DRAFT APPARATUS.

Specification of Letters iatent. Patented Aug. 20, 1912. p

. Application filed January 19, 1911. Serial No. 603,487.

arator to be again delivered and utilized 1n the furnace. It more particularly relates to improvements on prior patent application Serial No. 581,112, filed Sept. 8, 1910.

The objects of said improvements are to admit suflicient atmospheric air to the return duct carrying the said unburned matter to the furnace to promote the combustion of the same and raise the general efliciency of the furnace by admitting the same in a blast at the approximatepoint of combustion in the fire box.

The invent-ion consists in the novel ar-.

rangement and combination of devices, as will be hereinafter described and claimed.

Figure 1 is a View illustrating apparatus embodying our invention, partly in side elevation and partly in section, and, Fig. 2 is a horizontal sectional View of the se arating chamber taken on the line 22 0 Fig. 1, the smokeconduit being broken away.

The reference numeral 1 designates a smoke outlet of a boiler furnace 2 through which the draft is induced bymeans of power-driven blower 3. The conduit 4, through which said smoke is driven communicates tangentially with a separator 5 which 'centrifugally se arates the heavier particles from the smo e. Such particles are gravitated toward the bottom 6 of said separator where they are influenced by a exclusively, in power lants such as lumber manufactories where t he refuse wood material is burnedas fuel. Such material: is of relatively low fuel value and usually contains a considerable amount of moisture. An induced or other forced draft is generally employed to effect the necessary combustion of such relatively ineflicient fuel. Owing to the relatively high pressures ordinarily generated by the inducing blower, as 3, a considerable amount of such fuel is drawn through the flues in an unconsumed state in the form of cinders or unburned charcoal and ordinarily wasted. The escape of this carbonized fuel 1s a more serious loss than is usually considered as the same comprises a substantial proportion of the total amount of fuel deposited on the grates and a considerable absorption of heat has occurred in the drying of this fuel and the raising of the water vapor to the temperature of the combustion chamber. Such carbonized fuel is of high calorific value as it has been withdrawn from the fire-boxwhen at about the point of combustion and, when reentered, is in a condition to be easily kindled.

Approved devices for effecting the saving of the unburned particles accompanying the flue gases are disclosed in our said prior patent application. A further improvement and advance is effected by the adatation and arrangement of the discharge en 10 of said duct'8 in its entrance to the fire-box of the boiler furnace and provision for the admissionof atmospheric air into said duct to supply oxygen to the fire-box under the most favorable conditions for combustion purposes. communicating with the cinder separator and the boiler furnace at either end, we form an opening 11 provided with an adjustable 'cover 12 through which air may be atmospheric air admitted to a temperature highly conducive to combustion.

The proportionate amount of oxygen d1s- To that end, in the duct 8, 8',

coverable in the duct .8 before theadmission of air is about 12 per cent. which, after suchadmission, is raised to an approximate 17.5, per cent.; a gas not greatly inferior to air for supplying oxygen. At the same relative positions carbon-dioxid is reduced from 7.8 per cent. to 2.3 per cent. These gases with their accompanying carbonized particles. and in heated condition are introduced violently into t-he' furnace through the connection 10 anddirected by an interior nozzle (not shown) at a point where they may be most efficiently combined with the fresh gaseous distillations of the fuel and promotethe general combustion. Such point will usually be at or near thebridge wall of the furnace.

An analysis of the resultant gaseous products will disclose that approximately the equivalent of the oxygen admitted with the atmospheric air to the mixture has beenutilized in combustion. Practical tests also show that a greatly increased efficiency has been effected owing to the decrease of the total amount of air admitted to the firebox. This decrease occurs in the air drawn through the grates and consequently reduces I the amount of air requiring to be raised to a relatively high temperature before being available for combustion. Any excess-of air over the amount required for good combustion is disadvantageous as it but absorbs considerable amounts of sensible heat which escapes with the flue gas. In the present method a considerable proportion of such unchanged air is returned to' the fire-box with the accompanying cinders and in condition to combine readily with the gaseous distillations there encountered.

It may be stated that a considerable saving in power is efiected in operatin under the improved conditions described. ginaller quantities of flue gases are handled, a conwhich said Zl siderably reduced amount of air is drawn through the grates, therefore sufficient working pressures may be maintained within the flues although the speed of the blower 3 be substantially reduced,

What we claim, is

1. An apparatus for inducing furnace drafts comprising'the combination with afurnace provided with an outlet for. the products "of combustion, of a blower with outlet solely communicates, a separator, eans for discharging gases from the blower tangentially into the separator to separate the solid matter therefrom, a smoke stack depending into said separator, said separator having a closed bottom, a pipe com nicating with said separator at the botto thereof, asuction device in which said pipe opens, and a conducting pipe 1ead mg from said suction device to said furnace\ above the grate bars thereof. b

2. An apparatus for inducing furnace drafts comprisin the combination with a furnace provide with .an outlet for the products of combustion, of a blower with which said outlet solely communicates, a separator, means for discharging gases from the blower tangentially into the se arator to separate the solid matter there rom, a smoke stack depending into said separator, said separator -having a closed bottom, a pipe communicating with said separator at the bottom thereof, a suction device in which said pipe opens, a conducting pipe leading from .said suction .device to said furnace above the grate bars thereof, and regulatable means for admitting air to said suction device.

3. An apparatus for the purpose set forth comprising the combination with a furnace, of a blower, an outlet pipe for the products of combustion from said furnace, said outlet pipe communicating solely with said blower, a separator having a funnel-shaped losed lower end, means for establishing communication between the blower and the upper portion of said separator for discharging'the gases tangentially in the latter to separate the solid matter from'the gases, a smoke stack supported by and extending in said separator, a suction device, means for establishing communication between the bottom of the separator and said suction device, and means for establishin cation between said suction device and the furnace above the grate bars thereof.

4. An apparatus for the purpose set forth comprising the combination with a furnace, of a blower, an outlet pipe for the products of combustion from said furnace, said outlet pipe communicating solely with 4 said blower, a separator having a funnel-shaped closed lower end, means for establishing communication between the blower and the upper portion of said separator for discharging the gases tangentially in the latter to separate the solid matter from the gases, a smoke stack supported by and extending in said separator, asuction device, means for establishing communication between the bottom of the separator and said suction device, me'ans'for establishing communication between said suction device and the furnace "above the grate bars thereof, and a regulatable means for admitting air to said suction device.

5. An apparatus for the purpose set forth, comprising the combination with a furnace, of an outlet for the products of communicombustion from the furnace, means for I said suction device and said receptacle, means for establishing communication between said suction device and the furnace above the grate bars thereof, and a smoke stack communicating with and supported by said separating means.

6. An apparatus for the purpose set forth, comprising the combination with a furnace,

of an outlet for the products of combustionv from the furnace, means for separating the solid particles from the products of combustion, said outlet communicating solely with said means and discharging the gases tangentially into said separating means, a receptacle for receiving said separated particles, a suction device, means for establishing communication between said suction device and said receptacle, me ms for establishing communication betw 11 said suction device and the furnace above the grate bars thereof, a smoke stack communicating with and supported by said separating means, and regulatable means for admitting air to said suction device.

JOHN K. MILLER; ALLEN O. MILLER.

Witnesses H. BARNES, E. PETERSON. 

